/*
% Ambient Light.
date: 05/29/12
*/

/*****************Un-Twealables**********************************/
#define FLIP_TEXTURE_Y 0

//after colon is a semantic usefull later for knowing what variables this shader has
float4x4 WorldViewProjection : WORLDVIEWPROJECTION 
< 
	string UIWidget="None";// < = annoation only for FXCOMPOSER 
>; 

/****************Tweakables************************************/
texture ColorTexture : COLOR 
< 
	string ResouceName = "default_color.dds";
	string UIName = "Color Texture";
	string ResourceType = "2D";
>;

float4 AmbientColor : COLOR
<
	string UIName = "Ambient Light";
	string UIWidget = "Color";
	
> = {1.0f,1.0f,1.0f,1.0f}; //default value

/***************Un-Tweakable************************************/
sampler2D ColorSampler = sampler_state
{	
	Texture = <ColorTexture>; //the texture it will be grabbing pixel date from
	Magfilter = LINEAR;		  //zoom in - does linear interpelation
	Minfilter = LINEAR;		  //zoom out
	Mipfilter = LINEAR;
	AddressU = Wrap;		  //wrap or clamp
	AddressV = Wrap;		  //uv values or 0 to 1 oustide that they must either be wrapped(round up to the next) or clamped(made to fit in 0to1)
};

/*****************Data Structures****************************/
struct VS_INPUT
{
	float4 ObjectPosition: POSITION0;
	float2 TextureCoordinate : TEXCOORD0;
};
struct VS_OUTPUT
{
	float4 ScreenPosition: POSITION0;
	float2 TextureCoordinate: TEXCOORD0;
};
struct PS_OUTPUT
{
	float4 Color:COLOR0;
};

/*****************Utility Functions*************************/
float2 get_corrected_texture_coordinate(float2 textureCoordinate)
{
	#if FLIP_TEXTURE_Y
		return float2(textureCoordinate.x,1.0 - textureCoordinate.y);
	#else
		return textureCoordinate;
	#endif
}

/*****************Vertex Shader*****************************/
VS_OUTPUT vertex_shader(VS_INPUT IN)
{
	VS_OUTPUT OUT = (VS_OUTPUT)0; //memset clear garbage
	OUT.ScreenPosition = mul(IN.ObjectPosition, WorldViewProjection);
	OUT.TextureCoordinate = get_corrected_texture_coordinate(IN.TextureCoordinate);
	return OUT;
}

/*****************Pixel Shader*******************************/
PS_OUTPUT pixel_shader(VS_OUTPUT IN)
{
	PS_OUTPUT OUT = (PS_OUTPUT)0;
	OUT.Color = tex2D(ColorSampler, IN.TextureCoordinate);//tex2d(color sampler , texture)
	OUT.Color.rbg *= AmbientColor.rgb * AmbientColor.a; // color (.rgb) * Intensity(.a) -->swizzeling
	//cannot mix vector and color domain
	return OUT;
}

/****************Techniques**********************************/
technique main
{
	pass p0 
	{
		VertexShader = compile vs_3_0 vertex_shader();
		PixelShader = compile ps_3_0 pixel_shader();
	}
}
